A strong earthquake rocked a large swathe of northern Italy early on Sunday, causing at least three deaths and bringing about the collapse of rural factories and ancient bell towers in towns.

Italy 6 magnitude earthquake collapses builds in Bologna

The epicentre of the quake, which struck at 04:04 a.m. (0204 GMT) and had a magnitude of 6.0, was in the plains near Modena in the Po River Valley and the tremors were felt in nearby regions.

It was the strongest quake to hit Italy in three years.

One person working a night shift died in the collapse of a factory and two were killed when a modern ceramics factory made of steel crumpled.

Rescue officials were checking reports that other people were buried under rubble.

There was serious damage to historic buildings such as the 14th century Estense Castle in the town of San Felice Sul Panaro, near the epicentre.

There were fears that one of the towers of the famous mediaeval castle, the town’s biggest attraction, could collapse. The

Earthquake hits Bologna city, Italy - May 20

town’s main church was also severely damaged.

Thousands of people living in the area rushed into the streets after the quake, which shook the major towns of Bologna, Modena, Ferrara, Rovigo, Verona and Mantua. No serious damage was reported in the larger, heavily populated towns and cities.

A series of strong aftershocks hit the area, the strongest measuring 5.1, and local mayors ordered residents to stay out of their homes.

The quake was centred 22 miles (35 km) north-northwest of Bologna at a relatively shallow depth of 6.3 miles (10 km), the U.S. Geological Survey said.

The last major earthquake to hit Italy was a 6.3 magnitude quake in the central Italian city of L’Aquila in 2009, which killed nearly 300 people.

Italy Earthquake Latest News Update – In a Glance

Kills at least four and damages buildings across Emilia Romagna region